Process of coating metallic surfaces



United States Patent PROCESS OF COATING METALLIC SURFACES.

Application September 2, 1954, Serial No. 453,950

8 Claims. (Cl. 117'-62) No Drawing.

This invention relates to animproved process of coating metal surfaces with, compositions containing a polymer of 3,3-bis(chloromethyDoxetane as the film former and, more particularly, to a process of increasing the adhesion of the coating to the metal substrate and to the metal articles so. coated.

Polymers of 3,3-bis(chlorornethyl)oxetane having a molecular weight of at least 10,000 have physical properties that are .highly desired inprotective coatings for metallic and other surfaces, and compositions containing thesepolymers may be used for coating,metallic surfaces as, for example, iron, steel, aluminum, copper, tin plate, etc., cellulosic surfaces such as wood, paper, cardboard, cotton cloth or webbing, etc., glass, glass fibers, asbestos, textiles, and many other types of surfaces. Articles coatcdwith-a-filmof a polymer of 3,3-bis(chloromethyl) oxetane have a high degree ofchemical resistance, are not attacked by most solvents, and are impervious to water, air, etc. Hence, polymers of. 3,3-bis (ch1or0 methyl)oxetane .may be used. for boththe internal and external .coating ofchemical reactors, piping, metal containers, cardboard containers, etc.

Now, in. accordance with this. invention, it has been found that the. adhesionof the 3,-3-bis(chloromethyl) oxetane polymer coating on metal may be very greatly increased if, after applying the coating, it is fused at a temperature above the softening point of the polymer and; then is quenched. It wasmost unexpected to discover thatinstead of lifting the film from the substrate as was expected, the. film was more firmly, adhered to the substrate by this rapid cooling after fusion of the coating.

Any polymer of 3,3-bis (chloromethyl)oxetane, which may also be called 3,3-bis(chloromethyl)oxacyclobutane, having a molecular weight of at least 10,000 may be used in accordance with this invention to produce compositionssuitable for coatingin accordance with this invention. However, the higher the molecular, weight of the polymer, the better the general physical properties. Hence, higher molecular weight polymersare generally preferred for the coating compositions used in the process of-this. invention. Because the. molecular weightof the higher molecular weight polymers is not as .easily or accuratelydetermined, it is simpler to define the most useful polymers interms oftheir specific viscosities. Any polymer having a specific viscosity, when measured as a 1% solution incyclohexanone at. 50 C., of. atleast about. 0.3 may be used for the coating. compositions used in this invention.

The 3,3-bis( chloromethyl)oxetane polymers having molecular weights of 10,000 and above may be prepared by contacting 3,3-bis(chloromethyDoxetane with boron trifluor'ide or its molecular complexes. The structural formula of 3,3-bis(chloromethyl)oxetane is as follows:

ICC

The polymerization reaction is generally carried out in the presence of an inert organic liquid diluent- Any inert organic solvent may be used as the diluent for the polymer'ization. However, highly polarorganic solvents such as dioxane, etc., are preferably not used since they retard the polymerization by inactivating the catalyst. In addition, inorganic solvents such as liquid sulfur dioxide may also be'used. The solvent should, of course, not be one which will cause chain termination since such a solvent, as, for example, an alcohol, would not then be inert. Exemplary of the solvents which may be used for carrying out the polymerization of 3,3-bis(chloromethyl)- oxetane are the hydrocarbon solvents such as n-hexane, cyclohexane, benzene, toluene, etc., chlorinated solvents such as methylene chloride, chloroform, carbon tetrachloride, dichlorobenzene, etc., and nitro compounds such as nitropropane, nitrobenzene, etc. The catalyst may be added directly to the solution of 3,3-bis(chloromethyl)- oxetanein inert diluent or it may be added as a solution, if desired. Boron trifluoride may be added as a gas or if used in the form of one of its molecular complexes with an ether, acid, or salt, as, for example, boron trifiuoride etherate, etc., it may be added as a solution. The amount of catalyst which is added to the monomer may vary over a wide range but usually from; about 0.01% to about 10% is adequate and preferably an amount of from about 0.1% to about 4% basedon the monomer will be used. The amount of catalyst will, of course, vary with the type of polymerization reaction. For example, a lower range of catalyst concentration is required if the polymerization is carried out in the absence of a solvent and a higher concentration, of catalyst is used if the polymerization is carried out in the presence of a diluent.

The temperature at which the polymerization of 3,3- bis(chloromethyl)oxetane is carried out may vary over a wide range and is, in general, dependent upon the solvent used, etc. In general, the molecular weight of the polymer produced increases with a decrease in temperature.

Hence, for the production of higher molecular weight polymers, the temperature should be held below about C. Lowering of the temperature is limited by the type of solvent and the solvent-monomer ratio employed in the reaction since the monomer may tend to crystallize out of solution and hence polymerization might not proceed as rapidly. In general, the polymerization reaction will be carried out, by selection of appropriate solvent, etc., at a temperature within the range of from about 80 C. to about 80 0, preferably at a temperature below about 30 C. and more preferably at a temperature below about 20 C. The length of time that the polymerization reaction is carried out will, in general, vary from about /2 hour to 10 hours. Although the reaction mixture may turn solid very quickly, higherconversions may be obtained by allowing it to cure for several hours, the polymerization continuing in what is apparently a solid phase. The polymerization reaction may, of course, be performed in a batchwise manner or as a continuous reaction.

The manner in which the polymer is isolated will depend upon the type of polymerization system used. For example, if a large amount of solvent was used as a diluent, the polymer may be separated simply by filtration. Otherwise, it is readily isolated by treating the reaction mixture with a liquid in which the polymer is insoluble but which will destroy the catalyst which was used for the polymerization reaction. Alcohols such as methanol, ethanol, isopropanol, etc., are suitable for this purpose. The polymer then may be separated by filtration.

Polymers of 3,3-bis(chloromethyl)oxetane of any desired molecular weight may be prepared by the proper selection of the polymerization reaction conditions, as, for

example, control of temperature, etc. Another factor which enters into the molecular weight of the polymer obtained by this polymerization process is the purity of the monomer. As pointed out above, alcohols function as chain terminators in the polymerization reaction. Hence, if the monomer contains as an impurity any appreciable amount of chlorohydrin, the molecular weight of the polymer which is produced will be lowered. In the same way, the presence of alcohols, in general, and of any substantial amount of moisture should be avoided since they terminate the polymerization and also destroy the catalyst.

Another method of modifying the properties of the 3,3-bis(chloromethyl) oxetane polymer is by the incorporation of a copolymerizable monomer in the polymerization mixture so that a copolymer is produced. By this means it is often possible to modify the physical properties of the polymer in a desired manner for a specific use of the 3,3-bis(chloromethyl)oxetane polymer. For example, the softening point may be raised or lowered, flexibility increased, etc. Exemplary of the monomers that may be copolymerized with 3,3-bis(chloromethyl)oxetane are other 3,3-disubstituted oxetanes such as 3,3-bis(fluoromethyl)oxetane, 3,3-bis(bromomethyl)oxetane, 3-chloromethyl 3 methyloxetane, 3,3 dimethyloxetane, 3,3 bis(phenoxymethyl)oxetane, etc., and other copolymerizable monomers such as oxetane, and other substituted oxetanes.

The following examples will illustrate the preparation of the polymers of 3,3-bis(chloromethyl)oxetane from which the coating compositions used in this invention are prepared. All parts and percentages are by weight unless otherwise indicated.

Example 1 A solution of 1 part of 3,3-bis(chloromethyl)oxetane in 1 part of methylene chloride was treated at C. with 2.0% of boron trifluoride based on the monomer (added as a 25% solution of boron trifluoride etherate in methylene chloride). After standing for -7 hours at that temperature, methanol was added to the reaction mixture and the polymer separated by filtration. The conversion of monomer to polymer amounted to 80%. This polymer had a specific viscosity (1% solution in cyclohexanone) of 0.375. This corresponds to a molecular weight of 26,000.

Example 2 A solution of 1 part of 3,3-bis(chloromethyl)oxetane in 2 parts of chloroform was cooled to 35" C. and held at that temperature while a slow stream of nitrogen was passed through it, boron trifluoride being bled into the nitrogen stream at such a rate that the temperature elevation was maintained within one to two degrees. Within one-half hour the reaction mixture had become so viscous that it could no longer be stirred. It was then allowed to stand at 35 C. for 2 hours, after which the polymer was recovered by agitating the reaction mixture with methanol and filtering. The polymer was washed with methanol and dried in vacuo at 60 C. The white solid product so obtained had a softening point of 165-170" C. The specific viscosity of a 1% solution of it in cyclohexanone was 0.702 which corresponds to a molecular weight of about 42,000.

Example 3 The above example was repeated except that methylene chloride was used in place of chloroform and the temperature was held at 50 C. throughout the polymerization. The polymer so obtained had a softening point of about 165-170" C. and an intrinsic viscosity of 1.05 which ilso t )ec(1)1(1)i(;alent to a molecular weight of about 60,000 to Example 4 i A solution of 1 part of 3,3-bis(chloromethyl)oxetane 1n 2 parts of methylene chloride was cooled to -50 C,

and held at that temperature while a slow stream of nitrogen was passed through it, boron trifluoride being bled into the nitrogen stream at such a rate as to maintain the temperature within one to two degrees. The total amount of boron trifluoride used was 0.7% based on the weight of the monomer. At the end of 4 hours, the polymer was isolated as described in the above examples. The specific viscosity of a 1% solution of this polymer in cyclohexanone at 50 C. was 1.6.

Example 5 A solution of 1 part of freshly distilled 3,3-bis(chloromethyl)oxetane in 2 parts of methylene chloride was cooled to about 45" C. Boron trifluoride was bled into this solution as described in the foregoing examples until an amount of about 2.0% of boron trifluoride based on the Weight of the monomer had been added. After 1% hours the polymer was isolated. The conversion of monomer to polymer amounted to 74%. A 1% solution of this polymer in cyclohexanone at 50 C. had a specific viscosity of 2.3.

Example 6 A solution of 1 part of a carefully purified 3,3-bis(chloromethyl)oxetane in 2 parts of methylene chloride was cooled to 50 C. Boron trifluoride (1.0% based on the weight of the monomer) was then added as in the foregoing examples. After 1 hour the polymer was isolated. The specific viscosity of this polymer (1% solution in cyclohexanone at 50 C.) was 3.7.

Example 7 To a solution of 5.2 parts of 3,3-bis(chloromethyl)oxetane and 2.38 parts of 3,3-bis(fluoromethyl)oxetane in 14 parts of liquid sulfur dioxide cooled to 25 C. was added 0.12 part of gaseous boron trifluoride. After standing for 18 hours at that temperature, methanol was added and the polymer was separated by filtration, washed with methanol, and dried. The polymer obtained was a tough solid that softened at 110 C. and had a specific viscosity of 0.658 when measured as a 1% solution in cyclohexanone. It contained 29.2% chlorine and 11.1% fluorine.

Example 8 A mixture of 5.2 parts of 3,3-bis(chloromethyl)oxetane and 3.98 parts of 3,3-bis(bromomethyl)oxetane was polymerized as described in Example 7. The polymer so obtained was a powder having a melting point of 179-185 C. and a specific viscosity of 0.316 when measured as a 1% solution in cyclohexanone. It contained 26.6% chlorine and 26.9% bromine.

Example 9 A slow stream of nitrogen was passed into an agitated solution of 117 parts of 3,3-bis(chloromethyl)oxetane and 12 parts of 3-chloromethyl-3methyloxetane. After cooling to -30 C., 3.88 parts of gaseous boron trifluoride was introduced into the nitrogen stream. Polymerization was then allowed to proceed at that temperature for 4 hours after which 300 parts or methanol was added. The polymer was removed by filtration, washed with methanol, and dried. It was a powder having a melting point of 152-156" C. and a specific viscosity of 1.217 when measured as a 1% solution in cyclohexanone. It contained 43.6% chlorine.

Example 10 A slow stream of nitrogen was passed into a solution of 7.3 parts of dimethyloxetane and parts of 3,3-bis- (chloromethyl)oxetane in 210 parts of liquid sulfur dioxide and cooled to 30 C. Gaseous boron trifluoride, 3 parts, was then added and the polymerization was allowed to proceed at that temperature for 5 hours. Methanol, 300 parts, was then added and the polymer was separated by filtration, washed with methanol, and dried. It was a powder having a melting point of 159-163 C.

Wham-4s and a specific viscosity-of 0.9 99 whenmeasured as a 1% solution incyclohexanone. It contained 42.0% chlorine.

While these polymers have a high degree of heat stability, they are subject to degradation whenheated for long periods of time. Thus, if the-coated surface is one that will be subjected to 'constanth'eat as in chemical reactors, piping for hot liquids, articles that requires sterilization, etc., degradation of the polymer may occur resulting in the coating becoming brittle and cracking. Another type of degradation that may be encountered is that caused by exposure for long periods of time to light and particularly to ultraviolet light, as may be the case in manyapplications of these coatings, with the result that a considerable amount of discoloration may occur as well as loss in flexibility of the coating. Anysuchheat and/or light degradation may be avoided by the incorporation of a small amount of a phenolic stabilizer in the coating composition prior to coating" the article. Any phenolic stabilizer or ester or ether thereof may be used in the preparation of the compositions of this invention. Some of these phenolic compounds or esters or ethers thereof are more effective as heat stabilizers while others are more effective as light stabilizers although in many instances the compound will act as both. It may, therefore, be desirable to use more than one of the phenolic stabilizers. While any phenol will exert'some stabilization, the phenol will preferably contain at least one alkyl or cycloalkyl substituent, having at least 4- carbon atoms, or aryl substituent, or aralkyl substituent. Exemplary of the phenols, phenol esters, and phenol ethers that may be used as heat and/or light stabilizers for the polymers of 3,3- bis-(chloromethyl)oxetane are the highly substituted phenols such as di-tert-butyl-p-cresol, o,p-diamylphenol, oand p-tertamylphenol, p-octylphenol, benzoyl resorcinol (i. e., 2,4-dihydroxybenzophenone), p-cyclohexylphenol and the similarly substituted alkyl naphthols, etc., alkylenebisphenols such as 2,2-methylenebis(4-methyl-6- tert-butylphenol) 2,6-bis (2-hydroxy-5 metl1ylphenyl)- methyll-p-cresol, p,p'-isopropylidenebisphenol, p,p-secbutylidenebisphenol, 4,4'-isopropylidene-bis-o-cresol, etc., esters of phenols such as resorcinol monobenzoate, hydroquinone monobenzoate, propyl gallate, etc., and ethers of phenols such as the monobenzyl ether of hydroquinone, and the epoxy resins produced by the reaction of epichlorohydrin with various bisphenols such as p,p'-isopropylidene'bisphenol, p,p-sec-but'ylidenebisphenol, 4,4- isopropylidene-bis-o-creso1, etc. The amount of the stabilizer incorporated in the coating composition may be varied over a wide range and will depend upon the degree of stabilization desired,but, in general, an amount of from about 0.1% to about 10%, and preferably from about 1 to about by weight of the polymer of these phenolic stabilizers will adequately protect the fabricated articles from the degrading elfects-of heat, light, etc. A larger amount of stabilizer may be used if desired, but generally is not necessary. Also elfective as light stabilizers for the fabricated articles are inert materials such as fillers, pigments, etc.

Various other additives may be incorporated in the coating compositions used in the process of this invention. For many purposes it may be desirable to incorporate various fillers,- pigments, or other colorants, etc., not only as ultraviolet light screens but for coloring, etc. The amount of such materials which are added may, of course, be varied over a wide range. For example, for the preparation of colored materials, the amount of pigment, or other colorant such as dyes, added will obviously depend upon the degree or shade of color desired.

For some purposes it maybe desirable to incorporate a plasticizer in the coating compositions used in this invention. Many of the phenolic stabilizers mentioned above will also function as plasticizers for the coating compositions used in this invention if used in a sufiicient quantity, as, for example, when used in an amount of from about 5 to about of the polymer weight. Any

l-asti'eizer that is compatible with'the 3,3-bis-(chlorom'ethylyoxeta-ne polymer may be incorporated. Exemplary of such plasticizers are the alkyl esters-of carb'oxylic a'cidssuclr as the alkyl stea rates oleates, sebacates, adipates, phthala-tes, etc., as, for'example, amyl steara'te, butyl oleate, di-Z-ethylhexyl adipate, dibutyl sebacate, dioctyl phthalate, di-Z-ethyIheXyI phthalate, n-octyl n-decyl ph-thala te, glycerol triacetate, glycerol tripropionate, pentaerythritol diacet ate dibutyl-ate, dipenta'erythritol diac'etate dipropionate dibutyrate, and the pentaeryt-hritol tet'r'ae'ster of mixed Cato C9- acids, polyesters such as the polyester-'ofsebaci'c acidandethylene glycol, phosphates such-as tricr'esyl phosphate, cresyldiphenyl phosphates ethyl'hexyl diphenyl phosphate, hydrocarbon-oils such-as mineral oil, fluorinated chlorinated hydrocarbon oils,

chlorinated diphenyl, o-chloronaphthalene, polyethers such as the solid polyethylene glycols sold under the trade name, C'a'rbowax, and :other polymeric materials such. as styrene-acrylonitrile copo'lyme'rs, polydimethyloxetane (polymerized 3,3 -di'n-iethyloxetane) etc.

Any 'rnethod zof. applyingthecoating of. the 3,"3 b'is- (ehloro'rnethyl)oxetane polymer to the metal substrate may be'us'ed. Coatings of the polymer composition may be applied fromso'lution in a solvent for the composition,

as, for example, cyclohexanone, isophorone, etc., by hotbrnshing, spreading by means of a-blade, spraying of the. composition in molten form, flame-spraying, hotspray'ing, airless atomization, etc. The solution viscosity and concentration of: the material as applied to the substrate, where-the coating is applied as a-solution, are not critical but should be such as will give adequate flow and spreading atthe'temperatureat which it is applied. In general, the concentration'of the polymer in the solution willbe from about 5%=to a'b'out 30%, depending upon the viscosity of the polymer being used. Laminates may be prepared by building up the layers by coating each layer with a solution of the polymer or with molten polymer. They may also be formed by fusinglayers of dry polymer between the material to be laminated. If asolution-of the polymer was used in-applying the coating. composiby baking, ,or'fiash-fusing as with a flame, etc., at-any temperature above the softening point of the polymer, i. e., about- C., and. preferably within the range of from=about C. to-aboutZlO C. The time and temperature of thisfusionzstep are preferablyltept at the minimum that will insurecomplete fusion, i. e., in essentially a'molten' state. Obviously, the time required'for thisfusion'stepwilhdepend upon the substrate that is coated. For example, if the substrate were a thin sheet of copper, only a very short time would be required, whereas if the substrate were a heavy block of. steel, 21 longer time would'be required. Usually 3 to 10 minutes exposure .at temperatures of around 200 C. is adequate.

Immediately after fusion iscomplete, the coatingis quenched. Theshorter the length of time between the fusion operation and the quench the better. In general, thistime should be kept to less than about 1 minute, and preferably to within 30 seconds. The temperature of the quenc'hbath, i. e., the temperature to which the coating should be promptly reduced after fusion, should be within the range of from about 0 C. to about 30 C., and preferably from about 0 C. to about 15 C. The coated article need be held at the quench temperature only long enough to reduce the temperature to that of the quenching medium. It may then be removed and allowed .to stand at room temperature or above, up to about 125 (1:, :in-'

definitely. Any aqueous fluid may be used as the quench bath, as, for example, water, aqueous salt solutions, aqueous solutions of ethylene glycol, etc.

The following examples will illustrate the process of coating metal surfaces in accordance with this invention.

Examples 11-13 A 20% solution of a 3,3-bis(chloromethyl)oxetane polymer having a specific viscosity of 1.6 (1 solution in cyclohexanone at 50 C.) and containing 0.1% of 2,2- methylenebis(4-methyl-6-tert-butylphenol) in cyclohexanone was heated to 8090 C. and cast by means of a doctor blade on panels of cold-rolled steel, bonderized steel, and of aluminum. The coatings were dried for one hour at 60 C. and then fused for minutes at 204 C. Some of the panels were allowed to cool slowly in air, some were immediately plunged into water at 12 C., and others into water at 100 C. The coating films were approximately 0.001 inch thick. With each of these metals, those coatings cooled in the cold water were found to have greater adhesion to the metal than those cooled in air or treated in boiling water. The superior adhesion was demonstrated in the following ways: (a) coin-scratch test wherein the edge of a five-cent piece is dragged across the surface of the coating in an attempt to cut through and lift the film, (b) an impact test in which a 400-gram blunt-nosed projectile is dropped from a height of 2% feet onto the front and the back of the coated panel, and (c) by attempts to lift the coating film along its edge and to strip it from the substrate. By all these methods the rapidly cooled coatings were found to be more firmly adhered to the metal. One of the panels which had been rapidly cooled was subsequently exposed in an oven at 65 C. for 24 hours with no detectable change by the coinscratch or impact tests.

Example 14 A solution was prepared containing 15% of a 3,3-bis- (chloromethyl) oxetane polymer having a specific viscosity of 1.7 (1% solution in cyclohexanone at 50 C.) and containing 0.075% of 2,2-methylenebis(4-methyl-6-tertbutylphenol), 0.525% of a commercial epoxy resin (a reaction product of epichlorohydrin, and p,p-isopropyli- 'denebisphenol) sold by Carbide and Carbon Chemical Company under the name of Stabilizer A-S, in a solvent comprising 3 parts by weight of cyclohexanone and 1 part of xylene. This solution, maintained at a temperature of 8090 C., was applied to bonderized steel panels by dipping the entire panel and withdrawing it at a uniform rate. The panels were dried and then fused at 200 C. for 10 minutes. Some of the panels were immediately quenched in water at 13 C. while others were allowed to cool slowly in air. The coating films were 0.0003 to 0.0005 inch thick. The quenched coatings were found to have better adhesion by the coin-scratch test. One of the quenched panels was exposed in a 121 C. oven for one month with no detectable loss of adhesion or any other properties.

Example 15 The polymer solution described in Example 14 was applied to a plaque of cold-rolled steel using the same dipping technique as in that example. After drying, the coating was fused at 200 C. for 10 minutes and immediately (i. e., in less than 10 seconds) was quenched in water at 13 C. The film had a thickness of 0.0005 inch. This plaque was exposed in a humidity cabinet (49 C. and 100% R. H.) for one month. The only corrosion that occurred was at a few points along the edges of the plaque where the metal had not been covered in the coating operation. Corrosion was not propagated from these points underneath the film, which demonstrated the excellent adhesion of the film to the substrate. An unprotected plaque, exposed to the same humidity conditions, was badly rusted over its entire surface within two hours.

Examples 16 and 17 A 15 solution of a 3,3-bis(ehloromethyl)oxetane polymer having a specific viscosity of 0.5 (1% solution in cyclohexanone at 50 C.) and containing 0.01% of 2,2-methylenebis(4-methyl-6-tert-butylphenol) and 0.06% of the epoxy resin described in Example 14, in cycle hexanone was prepared. This solution was sprayed at a temperature of C. using a conventional hot-spray lacquer gun onto panels of bonderized steel and coldrolled steel. The coatings were air-dried, fused at 200 C. for 10 minutes, and then quenched at 12 C. A second coat was then applied in the same manner, after which the coatings were again dried, fused, and quenched. The coatings so obtained had a thickness of about 0.0008 inch. In both cases the coatings had good adhesion and good salt-spray resistance. In neither case was there any sign of cracking or crazing when the panel was bent over a Bell mandrel.

Example 18 Example 16 was repeated except that the solution was pigmented using 1 part of titanium dioxide for every 4 parts of the 3,3-bis(chloromethyl)oxetane polymer, so that the solution was approximately 16% solids. Two coats were applied to the panels of bonderized steel as in that example. The coatings so obtained had a thickness of about 0.001 inch. The coatings had good adhesion and good salt-spray resistance and did not crack or craze when bent over a Bell mandrel.

The advantages to be realized by subjecting coatings containing a polymer of 3,3-bis(chloromethyDoxetane to these steps of fusion followed by rapid quenching are many. Of prime importance is the great increase in adhesion of the coating to the substrate with a resultant increased durability, and resistance to blistering and to lifting through attack of moisture or corrosive substances. In addition, there is also obtained a greatly improved gloss and flexibility of the coating. The above examples have demonstrated the improved adhesion, durability, scuff resistance, and resistance to scratching and cutting on a variety of metal surfaces.

The process of this invention may be used for coating any metal surface of any type. While the foregoing examples have demonstrated the process applied to flat surfaces, it may be applied to curved or any other type of surface, as, for example, for coating Wires, rods, screens, fiat or curved sheet metal, etc. Polymers of 3,3-bis(chloromethyl)oxetane, being insert and nontoxic, are particularly outstanding for use in coating metal cans used as food containers. The container and food processing industries have long sought for a material that could be used to replace tin, a metal that is costly and in short supply. Many attempts have been made in the past to use plastic film-forming materials for this purpose, but the polymers of 3,3-bis(chloromethyl)oxetane are the first such materials that have the necessary resistance to corrosion, etc., imperviousness to liquids, etc., and adherence to the metal from which the can is fabricated to completely eliminate the necessity of tin-plating the metal prior to applying the coating. In the preparation of these coated cans, the sheet metal from which the can is fabricated may be coated as described above with the polymer coating composition and the cans then cut and fabricated, in which case the seams may be sealed by fusion and pressing of the polymeric coating, or by the usual soldering and stripping procedures, etc. If the cans are prefabricated, they may be coated by spraying, dipping, or by any other coating methods and then fused and quenched as described above. Many other applications for the use of these polymers for coating articles by the process of this invention will be apparent to those skilled in the art.

What I claim and desire to protect by Letters Patent is:

l. The process of coating metallic surfaces with a coating composition comprising a polymer of 3,3-bis- AAMA .about 30 C.

2. The process of coating metallic surfaces with a coating composition comprising a polymer of 3,3-bis(chloromethyl)oxetane, having a specific viscosity of at least about 0.3, when measured as a 1% solution of said polymer in cyclohexanone at 50 C., which comprises applying said coating composition to the metallic surface, heating the coating to a temperature above about 180 C., and quenching the coating in an aqueous medium to a temperature of from about C. to about 30 C.

3. The process of coating metallic surfaces with a coating composition comprising a polymer of 3,3-bis(chloromethyl)oxetane, having a specific viscosity of at least about 0.3, when measured as a 1% solution of said polymer in cyclohexanone at 50 C., which comprises applying a solution of said coating composition to the metallic surface, heating the coating to a temperature above about 180 C., and quenching the coating in an aqueous medium to a temperature of from about 0 C. to about 30 C.

4. The process of coating metallic surfaces with a coating composition comprising a polymer of 3,3-bis(chloromethyl)oxetane, having a specific viscosity of at least about 0.3, when measured as a 1% solution of said polymer in cyclohexanone at 50 C, which comprises applying a solution of said coating composition to the metallic surface, heating the coating to a temperature above about 180 C., and within a period of about 1 minute quenching the coating in water to a temperature of from about 0 C. to about 30 C.

5. The process of coating metallic surfaces with a coating composition comprising a polymer of 3,3-bis(chloromethyl)oxetane having a specific viscosity of at least about 0.3, when measured as a 1% solution of said polymer in cyclohexanone at C., which comprises applying said coating composition to the metallic surface, heating the coating to a temperature of from about C. to about 210 C., and quenching the coating in water to a temperature of from about 0 C. to about 15 C.

6. The process of coating metallic surfaces with a coat ing composition comprising a polymer of 3,3-bis(chloromethyl)oxetane having a specific viscosity of at least about 0.3, When measured as a 1% solution of said polymer in cyclohexanone at 50 C., which comprises applying a solution of said coating composition to the metallic surface, heating the coating to a temperature of from about 195 C. to about 210 C., and quenching the coating in water to a temperature of from about 0 C. to about 15 C.

7. The process of coating metallic surfaces with a coating composition comprising a polymer of 3,3-bis(chloromethyl)oxetane having a specific viscosity of at least about 0.3, when measured as a 1% solution of said polymer in cyclohexanone at 50 C., which comprises applying a solution of said coating composition to the metallic surface, heating the coating to a temperature of from about 195 C. to about 210 C., and within a period of about 1 minute quenching the coating in water to a temperature of from about 0 C. to about 15 C.

8. The process of coating metallic surfaces with a coat ing composition comprising a polymer of 3,3-bis(chloromethyl)oxetane having a specific viscosity of at least about 0.3, when measured as a 1% solution of said polymer in cyclohexanone at 50 C., which comprises applying a solution of said coating composition to the metallic surface, heating the coating to a temperature of from about 195 C. to about 210 C., and within a period of about 30 seconds quenching the coating in water to a temperature of from about 0 C. to about 15 C.

References Cited in the file of this patent UNITED STATES PATENTS 2,270,285 Frolich Jan. 20, 1942 2,330,333 Brubaker Sept. 28, 1943 2,462,048 Wyler Feb. 15, 1949 

1. THE PROCESS OF COATING METALLIC SURFACES WITH A COATING COMPOSITION COMPRISING A POLYMER OF 3,3-BIS(CHLOROMETHYL)OXETANE, HAVING A SPECIFIC VISCOSITY OF AT LEAST ABOUT 0.3, WHEN MEASURED AS A 1% SOLUTION OF SAID POLYMER IN CYCLOHEXANONE AT 50* C., WHICH COMPRISES APPLYING SAID COATING COMPOSITION TO THE METALLIC SURFACE, HEATING THE COATING TO A TEMPERATURE ABOVE THE SOFTENING POINT OF SAID POLYMER, AND QUENCHING THE COATING IN AN AQUEOUS MEDIUM TO A TEMPERATURE OF FROM ABOUT 0*C.TO ABOUT 30* C. 